Electron discharge apparatus



Dec. 30, 1947, A. M. SKELLETT l ELECTRON DISCHARGE APPARATUS Fil ed Aug. 29, 1942 -2 Sheets-Sheet 1 Ilan,

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IN1/wmp A, M SKELLVErr ATT ORNE V Dec.,30, 1947. l A. M.sKE| LETT l l 2,433,403

ELEGTRON DISCHARGE APPARATUS Filed A115729, 1942 2 sheets-sheet 2 ELECT/90N @nu i 2/8L 1 2/8a.

/NvEA/rof? A. M SKELLE 7' T QAM@ 6.1M

ATTORNEV Patented ec. 3Q, 1947` Y Y artesana;Y ELnc'rRoN DISCHARGE APPARATUS Albert M. skeuett, Masi-son, N. J., assigner to Bell Telephone Laboratories,Incorporated, New York, N. Y., a corporation ofNewYork 9, 1942, serial@Nel.195116,67o

Application August 2 9 claims.- oiaslpzvr f This invention relates to electron discharge apparatus and more particularly to electron discharge devices of the rotating beam type.

One general object of this invention is to facili- .;tate the reiiicient -generation of a rotating electron beam inleiectron ldischarge devices suitable for use as frequency multipliers,- pulse generators,

receivingand; ltransmitting distributors for multiplex telephony, electr onicswitches' oscillation generators and the like. v

More specicallyfobjectsof this invention are to Increase the operating frequency range of apparatus including electron discharge devices of the rotating beam type;

.Enable Vthegeneration `of :an electrostatically l focussed rotatingelectron beam;

l Improve the operating eiciency of rotating I beam electron discharge devices; and

Y Simplifythe construction of such devices. vIn.one illustrativeV embodiment of this invention, `an electron, discharge device comprises an anodeV structure, ,which may include one or several elements, and an electrode system for pro- .ducing a concentrated electron beam rotating r,about an axis of the anode structure. This system includeagenerally, a cathode, a focussing electrode or ,grid encompassing andcoaxial with v the cathode, and a field electrode structure encompassing and coaxial with the control electrode .@or grid,'this structure including a plurality of electrically individual elements in edge to edge relation and extending substantially parallel to the cathode.

In accordance-with one feature of this invention, the elements of the held electrode structure are energized with alternating potentials in such manner as to produce an electric eld substantially parallel to a diameter and rotating at a uniform rate about the cathode, and the control relative to the cathode and eld electrode structure that the electrons emanating from the cathode are concentrated into a single, radial rotating beam substantially focussed upon the field electrode structure.

The invention and the above noted and other features thereof will be understood more clearly and fully from the following detailed description with reference to theaccompanying drawing, in which: l y

Fig. l is an elevational view in perspective of an closing vessel and .of the anode andfieldjelectrode structures being broken away to show the internal construction more clearly;

Fig. 2 is a diagrammatic end view oi the elec- Xtrodesinjth'e devicelillust'rated' iii-Fig. l showing ielcongurationand relation'of the electrodes;

2Fig. 3'is a circuit-diagram illustrating one'mani ner of operatingfthe `electron discharge device illustrates innige; 1 and 2; 7r

" Figsrf'fi and '5i airefldiagrammatic'plan views;v of

the electrode arrangements in discharge. devices illustrativeiofffotlleiA embodiments of this inven- `tion, fsuitable vv:for usefaslse'nding and receiving distributors-re pectively in" multiplex telephone Fig; 6 is 'fa circuit diagram' of-a frequency multiplier illustrative for another embodiment ott-his invention; Y

Fig. -'7 -isfa'perspectiverview of a held electrode "st'ructuref particularlysuitable for Vuse in a frequenc'y multiplier constructed inaccordance with this invention; and

Figi 8 is'aperspectiveview of a high frequency f" oscillation :generator illustrative of another embodimentof this invention. f

Referring now to the drawing, the electron disj charge device shown on Fig. 1 comprises an evacuated enclosing vessel" II) having a stem II provided with an annular 'flange I2 land mounting an velectrode assembly.- Thev electrodeassembly includes a .pair ofjparallel'insulating members I3 andA It, such asgmicaj discs-,ka cylindrical cathode l "l5, which inay'rbe of'ithe indirectly heated equipotential type, extendingthrough central apertures inthe discs I3 and IlIyand a helical focussingelectrode or grid I6 encompassing and coaxial with the cathode. The electrode orA grid l 6 is carried by'a pair ofv uprights Il fitted in diametrically aligned` apertures lin the discs I3 and 40' electrode or grid is operated at such potential lathe uprights vI'I being skewed or twisted as shown so'that e'acli extends from a pointat one end oi the grid to' a diametricallyopposite point atthe' other end ofthe grid,- whereby the intershortA Irigid wires IS secured theretoland fitted in Vc'eptionlof. electrons'by the uprightsV is substanftially' thesame around the cathodel The electrode assembly includes also a field electrode structure Vwhich-includes a plurality of similar equally spaced, arcuate plate members ISU, '-toI 8f inclusive; parallelv toI the` cathode and mounted in a cylindrical boundary vcoaxial` therewith. The plate membersl are mounted by i the "discs -I3 `and fllt, and have connecte'dthereto electron discharge device illustrative of one em- I bodiment oi this, invention, a portion of the envindividual leading-in"4 conductors 20 extending from the flange I2. The plate niei-nberV Idd is provided with a central aperture or slit 2| opposite which there is mounted, by pins 22 iltted in the discs I3 and I4, an anode 23, the anode having a leading-in conductor 24 connected thereto. Y

During operation of the device, as illustrated in Fig. 3, the field electrode plate members are supplied by a three phase source through transformers T, the mid-points of the secondary windings of which are connected to ground. The focussing electrode or grid I6 is biased at a positive potential V2 with respect to the cathode I5, by a battery 25 and also is biased at a positive potential V1 with respect to the eld electrodes I8, by a battery 26. The cathode I5, it will be noted. is thus biased positive with respect to the eld electrodes. The anode 23 is operated positive with respect to the cathode I5 as by a battery 27.

Because of the manner of energization of the plate members I8 and the focussing electrode or grid I6, the electrons emanating from the cathode I5 are concentrated into a single radial electron beam substantially focussed upon the boundary in which the plate members I8 lie and rotating clockwise as indicated by the arrow in Fig. 3. The beam impinges upon the plate members in sequence and when it crosses the aperture or slot 2l an electron current flows to the anode 23 so that a pulse, the length of which is dependent upon the width of the aperture or slit 2| and the rate of rotation of the beam, is produced in the output circuit connected between the cathode I5 and the anode 23. The frequency of the pulses produced will be dependend upon the rate of rotation of the beam.

The manner of operation of the rotating beam producing system will be understood from the following considerations with particular reference to Fig. 2, the plate member I8 being energized in the manner shown in Fig. 3. Ideally, the potential around the eld electrode structure varies according to the relation V=Vm cos 6 (1) where V is the potential of any point immediately adjacent this structure, Vm is the maximum potential applied and is the azimuthal angle around the longitudinal axis of the structure, measured, for example, from the X aXis'in Fig. 2. If the cathode I and control grid I6 were absent, this potential distribution would produce within the cylindrical boundary in which the plate members I8 lie, a plane uniform electric eld E parallel to the X axis. For purposes of analysis, this boundary may be replaced by two line images within the space occupied by the grid, considered as a simple cylinder, for these would give a cylindrical equipotential surface at the position of this grid cylinder. If the potential at the grid cylinder is zero, this analysis gives for the potential V'rat any point outside thereof Where E is the eld, Rz is the radius of the iield 4 electrode cylinder and the logarithm is to the base e. The corresponding potential at any point in this ield is R V=f i VcdrR I 2 r log l If the eld electrode cylinder is at zero potential Hence, from Equations 2 and 5, the total i'leld outside of the grid cylinder is given by d -dKTF=2E cos I9- (7) The gradient around the cylinder is zero when the right-hand side of Equation 7 is zero. 0 is the angle at which the gradient changes sign. Hence, electrons emanating from the cathode I5 can, at any instant, pass through the grid in a region covering an angle of about 20. Because of the positive potential of the grid I6, the electrons have a certain energy at the grid and, therefore, the emergence angle will be slightly greater than the size noted. However, it will be appreciated that a substantial portion of the electrons emanating from the cathode are concentrated into a beam which rotates with the rotating eld due to the alternating potentials applied tothe plate members I8 and which is substantially focussed upon the boundary in which these plate members lie.

In the analysis given above, the idal potential variation around the eld electrode structure has been assumed. In actual devices, because of the finite number of plate members and relatively small number of phases employed, this variation is only approximated and, therefore, some distortion of the field near the eld electrode members results but the effect of this distortion is to increase the focussing action when the beam is near the center of each of the plate members I8.

The beam current and the focussing are dependent upon the diameter of the focussing electrode or grid I6 and upon the potential Vi of this electrode with respect to the plate members I8 and the potential V2 of this electrode with respect to the cathode. In general, it is advantageous to make the grid of very small diameter. Very small grids can be used by employing a lamentary cathode, for example, a thoriated tungsten lament, and a sharp focus and large beam currents thus realized.

The optimum grid potentials will be dependent upon the size of the device. In general, the bias V2 of the grid with respect to the cathode should be small, for example a few volts, and the potential Vi should be of the order of live to ten times V1 and of the order of 1/5 the maximum value of VP the alternating potential applied to the plate members .I 8. Inaparticular construction where,- in the eldelectrode structurewas 0.96 inch in diameter, theg'rid 0;093 inch in diameter and the cathode v0.055 inch in diameter, the following potentials were found to be suitable: VP=225 volts, Vizapproximately 40-vo1ts and Vz=al0 proximately 5 volts.

Although inthe device shown in Fig. l and described hereinabove, only one of the plate members ISis providedl with anaperture or` slit 2|, several or all of the plate members-may be so. constructed. and individual anodes in cooperation with each aperture or slit or a single anode opposite all of the aperturesor slits maybe provided. Two such constructions are-illustrated in Figs. 4land 5.

Infthe construction illustrated in/Fig. 4, which is particularly suitable for use as a twelve channel sending distributor in multiplex telephone systems, each of the plate members IIBa to I8f inclusive of the eld electrode structure is provided with two apertures or slits IZI, similar to the aperture or slit 2| in the device shown in Fig. 1, and is provided also with a lip, portion 3! overlying the opening between it and an adjacent plate member to intercept electrons passing through this opening. Mounted behind each aperture or slit I2I is a control electrode or grid 3| for controlling the current passing through the respective aperture or slit. The control grids 3l are encompassed by ak cylindrical output anode 32 coaxial with the cathode.

As in the device shown in Figs. land 3, the focussing electrode or grid I6 and` thei plate members IIS are energized to produce a rotating beam substantially focussed upon the cylindrical boundary in which the plate members lie. As the beam rotates, electrons pass through the apertures or slits I2I and the current from each slit is varied in accordance with ldesired signals by the corresponding control electrode or grid 3|, which may be connected to a subscribers station, so that the current to thel output anode 32 is a complex current composed of the several varied currents. y

In the twelve channel receiving distributor illustrated in Fig. 5, the eld electro-de structure is the same as that .in the sending distributor shown in Fig. 4. However, in the receiving distributor, twelve output anodes 33 are provided, each ybeing positioned opposite a corresponding one of the apertures on slits I2`I and connected to a corresponding subscribers station. As in the sending distributor, the field electrode structure in the receiving distributor is energized to produce a rotating electron beam, which revolves in synchronism with the beam in the associated sending distributor. The signal applied to the focussing grid I6 of the receiving distributor corresponds to the complex current transmitted from the anode 32 of the sending distributor and the beam current to each of the anodes 33, therefore, corresponds to the respective variable current component of the transmitted current.

Although the invention has been described thus far as embodied in three phase devices including six plate members in the eld electrode structure, it will be understood that it may be utilized in other phase devices. In general, the number of plate members included Yin the eld electrode structure will be twice the number of phases.

Also, although the devices described thus far have used a polyphasel supply source for the field electrode structure, asingle phase supply may be employed. YO'rie such arrangement, suitable 6' for-,frequency multiplication, is illustrated in. Fig'. 6. In the device shown in this ligure, the eld electrode structure comprises four segments Y2|8 t to 2| 8d, the construction oi which is shown in Fig. 7, mounted in a cylindrical boundary encompassing and `coaxial with the vcathode I5 and focussing electrode or grid I6. Each of the seglments 2 I8 is provided with two apertures or slits 22| and with cut-out portions 35, juxtaposed cutout portions of adjacent electrodes dening an aperture similar to the apertures 22|, so that twelve similar, equally spaced apertures are pro'- vided in the eld electrode structure. This struc.- ture is encompassed by a cylindrical anode 36'.

The four segments ZIB are energized through transformers T, from a low frequency input,the phase of which is split into two components in time quadrature lby condensers 3l, one component being impressed between the segments 2I8df and 2 I8c and the other being impressed between the segments |811 and 2|8d. 'The focussing'grid I6 is biased at positive potentials with'respect to both the cathode I5 andthe eld electrodes and the output is taken from atransformer T2.

When the field electrode elements ZIB andthe Vgrid I6 are energized, there is produced a rotating electron beam focussed upon the boundary in which the eld electrodeelements lie. As the beam rotates it passes across theap'ertures in the field electrode structure so that, for each revolution of the beam, twelve current pulses are delivered'to the anode 35 and the outputffrequencyl is twelve' times that of the input(u A greater or lesser number oi apertures may be provided in the field electrode structure depending upon the harmonic of the input'fredue'ncy desired in the output.

The invention may be embodied also in ultrahigh frequency oscillation generators, one suitable construction forthis purpose being illustrated in Fig. 8. In this figure, 3S is a cylindrical metallic wave guide having therein an evacuated section bounded by the guide and vitreous closure'mem'- bers 39 and @il hermetically sealed thereto. Mounted within the evacuated section are a cathode I5 and focussing grid i6 which are maintained in coaxial relation with each other by insulating discs -iI and 42. The insulating disc il is mounted by an insulating spacer d3 Yengaging the inner wall ofthe guide 3S and the disc (i2 is mounted by a metallic disc i4 joined to the guide 3d so that the'cathode and grid are positioned coaxially with lthe guide 38.

As is known in the art, there may be set up in the cylindrical wave guide a simple type of oscillation in which two points at the extremities of a diameter have'the maximum'potential difference between them and to set up simultaneously a similar mode of oscillation in a directionat right angles to the direction of the first Voscilla'- tion. The net result vof these two modes'of 'sc'il lation is a rotating electric field in the guide at right angles to the longitudinal axis of the guide. Such eld, in the same manner as inthe devices described hereinabove, would resultinthe generation of a substantially radial electronv beam revolving about'tne cathode I5 as an axis. v Ogf course, the electron transit time from the cathode to the guide wall should be adjustedso that the electrons reach the wall when the potential thereof is negative with respect to the grid ItA to provide the negative resistance characteristic requisite for the generation of oscillations.

During operation of the device, the grid -I isY biased at a relatively low positive potential with out departing from the scope and spirit of this invention as defined in the appended claims.

What is claimed is:

1. In electron discharge apparatus, means for producing an electron beam rotating about an axis and extending normal to the axis, comprising a cathode extending along said axis, a eld electrode structure including a plurality of electrode members mounted side by side in a cylindrical boundary encompassing said axis, means for energizing said electrode members to produce Within said boundary an electric field substantially normal to and revolving about said axis, a focussing electrode adjacent said cathode, and means biasing said focussing electrode at a positive potential with respect to said cathode and said cathode at a positive potential with respect to said electrode members.

2. In electron discharge apparatus, means for producing an electron beam rotating about an axis, comprising a rectilinear cathode extending along said axis, a eld electrode structure including a plurality of plate member-s substantially parallel to said cathode and mounted side by side in a cylindrical boundary encompassing and coaxial with said cathode, alternating current potential means, connected to said plate members for producing within said boundary an electric field substantially normal to said cathode and revolving thereabout, a cylindrical focussing electrode adjacent, encompassing and coaxial with said cathode, and means biasing said focussing electrode at a positive potential with respect to said cathode and at a higher positive potential with respect to said plate member.

3. In electron discharge apparatus, means for producing an electron beam rotating about an axis, comprising a rectilinear cathode extending along said axis, a held electrode structure comprising a plurality of pairs of electrode members substantially parallelto said cathode and mounted side by side in a cylindrical boundary encompassing and coaxial with said cathode, polyphase f potential means having one phase connected between each pair of electrode members for producing within said boundary a radial electric field rotating about said cathode, a helical focussing grid encompassing and coaxial with said cathode, means biasing said grid at a potential several volts positive with respect to said cathode, and

'means biasing said grid positive with respect to said electrode members at a potential greater than said first potential and substantially smaller than the peak voltage of said polyphase potential means.

4. Electron discharge apparatus comprising a cathode, a cylindrical eld electrode structure encompassing and coaxial with said cathode and including a plurality of plate members, said field electrode structure having an aperture therein, an anode mounted opposite said apertureoutside of said eld electrode structure, means for energizing said field electrode structure to produce between it and said cathode a radial electric eld revolving about said cathode whereby electrons emanating from said cathode are concentrated into a radial beam rotating about said cathode, and means for focussing the electron beam upon said eld electrode structure including a cylindrical grid adjacent and encompassing said cathode and means biasing said grid at positive potentials and with respect to said cathode and said eld electrode structure.

5. Electron discharge apparatus in accordance with claim 4 comprising a control electrode mounted between` said anode and said aperture.

6. Electron discharge apparatus comprising a cathode, a cylindrical field electrode structure encompassing and coaxial with said cathode and having therein a plurality of apertures in alignment with said cathode, alternating current means for energizing said structure to produce a radial electric field substantially normal to said cathode and revolving about said cathode, a focussing grid adjacent and encompassing said cathode, means biasing said grid at positive potentials with respect to said cathode and said eld electrode structure, an anode outside of said structure and having portions opposite all of said apertures, and an output circuit connected to said anode. I

7. Electron discharge apparatus in accordance with claim 6 comprising a plurality of control electrodes each opposite a corresponding one of said apertures.

8. Electron discharge apparatus comprising a cathode, a cylindrical rleld electrode structure encompassing and coaxial with said cathode, said structure comprising pairs of arcuate plate members mounted side by side and each having a plurality of apertures therein, means for impressing low frequency alternating potentials between said pairs of plate members phasically related to produce within said structure a radial electric field rotating about said cathode, a cylindrical anode encompassing said structure, a high frequency output circuit connected to said anode, and a focussing electrode adjacent said cathode.

9. In electron discharge apparatus, means for producing an electron beam rotating about an axis, comprising a cathode extending along said axis, a cylindrical field electrode structure encompassing and coaxial with said cathode, means for energizing said structure to produce a radial electric field rotating about said cathode whereby electrons emanating from said cathode are concentrated into a beam extending substantially radially from said cathode and revolving about said cathode, and means for focussing said beam upon said structure including a grid encompassing and coaxial with said cathodeand biased at a positive potential with respect thereto.

ALBERT M. SKELLETT.

REFERENCES CITED The following references are of record in the file of this patent:

UNTED STATES PATENTS Number 

